COMPARISON OF PHYSIOLOGICAL REACTIONS AND PHYSIOLOGICAL STRAIN IN HEALTHY MEN UNDER HEAT STRESS IN DRY AND STEAM HEAT SAUNAS

2014 ◽  
Vol 31 (2) ◽  
pp. 145-149 ◽  
Author(s):  
Wanda Pilch ◽  
Zbigniew Szyguła ◽  
Tomasz Palka ◽  
Paweł Pilch ◽  
Tomasz Cison ◽  
...  
Keyword(s):  
Heat Stress ◽  
Physiological Strain ◽  
Healthy Men ◽  
Physiological Reactions ◽  
Steam Heat

Thermoregulatory, cardiovascular, and psychophysical response to alcohol in men in 40 degrees C water

1992 ◽  
Vol 72 (6) ◽  
pp. 2099-2107 ◽  
Author(s):  
T. G. Allison ◽  
W. E. Reger
Keyword(s):  
Heat Stress ◽  
Sweat Rate ◽  
Cardiovascular Response ◽  
Water Immersion ◽  
Rate Pressure Product ◽  
Esophageal Temperature ◽  
Healthy Men ◽  
Cardiovascular Stress ◽  
Rate Of Increase ◽  
Normal Relationship

The goals of the study were to test the hypotheses that ethyl alcohol (ETOH) in low-to-moderate doses would alter thermo-regulation and/or disrupt the normal relationship between physiological and psychophysical indexes of heat stress during 40 degrees C water immersion and to characterize the cardiovascular response to the combined stimuli of heat, water immersion, and ETOH. Six healthy men underwent three trials of 21 min of immersion in water at 40.0 +/- 0.1 degrees C after consuming 0, 0.27, or 0.54 g ETOH/kg. Esophageal temperature (Tes) rose by approximately 1.0 degrees C during immersion for each trial. Per unit of Tes rise, changes during immersion in skin temperature, sweat rate, heart rate, systolic and diastolic blood pressure, and psychophysical assessments of comfort and overheating did not differ significantly by trial. Across trials, there was an apparent threshold for activation of thermoregulatory responses at an approximately 0.5 degrees C increase in Tes occurring after approximately 9 min of immersion. This threshold was identified psychophysically by increased ratings of overheating and decreased comfort. Above the threshold, there was an attenuation of the rate of increase of Tes. Cardiovascular stress was mild (rate-pressure product approximately 12,000) and not significantly increased by ETOH. Hypotension and tachycardia when subjects stood to exit the tub were observed. The data suggest that ETOH at the doses administered does not affect thermoregulatory, cardiovascular, or psychophysical indexes of heat stress during 40 degrees C water immersion.

Occupational Hot Exposures: Body Physiology and An Approach to Numerical Assessment

1989 ◽  
Vol 203 (3) ◽  
pp. 133-141 ◽  
Author(s):  
R C McLean ◽  
G H Galbraith ◽  
D Stewart
Keyword(s):  
Heat Stress ◽  
Working Conditions ◽  
Heat Balance ◽  
Energy Exchange ◽  
Environmental Parameters ◽  
The Body ◽  
Assessment Procedure ◽  
Exchange Processes ◽  
Numerical Assessment ◽  
Physiological Reactions

This paper summarizes the factors which influence the energy exchange processes between an individual and his surroundings and the mechanisms by which the body attempts to maintain itself in a heat balance situation. Thereafter, the important physiological reactions to hot working conditions are described and, on this basis, a numerical assessment procedure is proposed. Examples are given of the use of this method in investigating the possibility of heat stress and estimating the time for which an acclimatized worker can safely be exposed in such circumstances. An increase in the permissible exposure time through a manipulation of the environmental parameters is also considered.

scholarly journals Relationship between heat storage and parameters of thermotolerance and fatigue in exertional-heat stress

2021 ◽  
pp. 99-99
Author(s):  
Sinisa Masic ◽  
Sonja Marjanovic ◽  
Jelena Maric ◽  
Vanja Jovanovic ◽  
Mirjana Joksimovic ◽  
...  
Keyword(s):  
Heat Stress ◽  
Perceived Exertion ◽  
Heat Storage ◽  
Stress Test ◽  
Physiological Strain ◽  
Blood Concentrations ◽  
Fatigue Development ◽  
The Relationship ◽  
Exertional Heat Stress ◽  
Peripheral Markers

Background/Aim. The risk assessment of heat illness and fatigue development is very important in military services. the aim of our study was to investigate the relationship between heat storage and various psychophysiological parameters of heat stress, as well as potential peripheral markers of fatigue in soldiers performing exertional heat stress test. Methods. 15 young, healthy and unacclimatized men underwent exertional heat stress test (EHST) with submaximal work load in warm conditions (WBGT 29 ?C) in climatic chamber. Every 5 minutes following parameters of thermotolerance were measured or calculated: core temperature (Tc), mean skin (Tsk) and body temperature (Tb), heart rate (HR), heat storage (HS), physiological strain index (PSI), as well as peripheral markers of fatigue (blood concentrations of ammonia, urea nitrogen (BUN), lactate dehydrogenase (LDH), cortisol and prolactin) and subjective parameters: thermal sensation (TS) and rate of perceived exertion (RPE). Results. Tolerance time varied from 45-75 minutes (63?7,7 min). Average values of Tc, Tb, and HR constantly increased during EHST, while Tsk after 10 minutes reached the plateau. Concentrations of all investigated peripheral markers of fatigue were significantly higher after EHST compared to baseline levels (31,47?7,29 vs. 11,8?1,11 ?mol/l for ammonia; 5,92?0,73 vs. 4,69?0,74 mmol/l for BUN, 187,27?28,49 vs.152,73?23,39 U/l for LDH, 743,43?206,19 vs. 558,79?113,34 mmol/l for cortisol and 418,08?157,14 vs. 138,79?92,83 ?IU/mL for prolactin). Conclusions. This study demonstrates the relationship between heat storage and Tc, HR, TS and RPE, but also with PSI. Concentrations of cortisol and especially prolactin showed significant correlation with parameters of thermotolerance.

scholarly journals Effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men

2016 ◽  
Vol 18 (2) ◽  
pp. 155
Author(s):  
Angelo Ruediger Pisani Martini ◽  
João Batista Ferreira-Júnior ◽  
Daniel Barbosa Coelho ◽  
Diego Alcântara Borba ◽  
Leonardo Gomes Martins Coelho ◽  
...  
Keyword(s):  
Heart Rate ◽  
Rectal Temperature ◽  
Heat Storage ◽  
Human Head ◽  
Physiological Strain ◽  
Strain Index ◽  
Healthy Men ◽  
Thermoregulatory Responses ◽  
Head Hair ◽  
Physiological Strain Index

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p155 The aim of the present study was to evaluate the effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men. Twelve healthy males (29.5 ± 3.7 years, 174.9 ± 4.3 cm, 72.7 ± 3.2 kg and VO2max 44.6 ± 3.4 ml.kg-1.min-1) participated in two self-paced outdoor 10-km running trials separated by 7 days: 1) HAIR, subjects ran with their natural head hair; 2) NOHAIR, subjects ran after their hair had been totally shaved. Average running velocity was calculated from each 2-km running time. Rectal temperature, heart rate and physiological strain index were measured before and after the 10-km runs and at the end of each 2 km. The rate of heat storage was measured every 2 km. The environmental stress (WBGT) was measured every 10 min. The running velocity (10.9 ± 1 and 10.9 ± 1.1 km.h-1), heart rate (183 ± 10 and 180 ± 12 bpm), rectal temperature (38.82 ± 0.29 and 38.81 ± 0.49oC), physiological strain index (9 ± 1 and 9 ± 1), or heat storage rate (71.9 ± 64.1 and 80.7 ± 56.7 W.m-1) did not differ between the HAIR and NOHAIR conditions, respectively (p>0.05). There was no difference in WBGT between the HAIR and NOHAIR conditions (24.0 ± 1.4 and 23.2 ± 1.5ºC, respectively; p=0.10). The results suggest that shaved head hair does not alter running velocity or thermoregulatory responses during 10-km running under the sun.

Aging and assessment of physiological strain during exercise-heat stress

2002 ◽  
Vol 282 (4) ◽  
pp. R1063-R1069 ◽  
Author(s):  
Daniel S. Moran ◽  
W. Larry Kenney ◽  
Jane M. Pierzga ◽  
Kent B. Pandolf
Keyword(s):  
Heat Stress ◽  
Hormone Replacement Therapy ◽  
Replacement Therapy ◽  
Aerobic Training ◽  
Aerobic Power ◽  
Hormone Replacement ◽  
Cycle Ergometer ◽  
Maximal Aerobic Power ◽  
Physiological Strain ◽  
The Third

The purpose of this study was to evaluate the physiological strain index (PSI) for different age groups during exercise-heat stress (EHS). PSI was applied to three different databases. First, from young and middle-age men (21 ± 2 and 46 ± 5 yr, respectively) matched ( n = 9 each, P > 0.05) for maximal aerobic power. Subjects were heat acclimated by daily treadmill walking for two 50-min bouts separated by 10-min rest for 10 days in a hot-dry environment [49°C, 20% relative humidity (RH)]. The second database involved a group ( n = 8) of young (YA) and a group ( n = 7) of older (OA) men (26 ± 1 and 69 ± 1 yr, respectively) who underwent 16 wk of aerobic training and two control groups ( n = 7 each) who were matched for age to YA and OA. These four groups performed EHS at 36°C, 40% RH on a cycle ergometer for 60 min at 60% maximal aerobic power before and after training. The third database was obtained from three groups of postmenopausal women and a group of 10 men. Two groups of women ( n = 8 each) were undergoing hormone replacement therapy, estrogen or estrogen plus progesterone, and the third group ( n = 9) received no hormone replacement. Subjects were over 50 yr and performed the same EHS: exercising at 36°C, 40% RH on a cycle ergometer for 60 min. PSI assessed the strain for all three databases and reported differences were significant at P < 0.05. This index rated the strain in rank order, whereas the postacclimation and posttraining groups were assessed as having less strain than the preacclimation and pretraining groups. Furthermore, middle-aged women on estrogen replacement therapy had less strain than estrogen + progesterone and no hormone therapy. PSI evaluation was extended for men and women of different ages (50–70 yr) during acute EHS, heat acclimation, after aerobic training, and inclusive of women undergoing hormone replacement therapy.

The Influence of Hot Humid and Hot Dry Environments on Intermittent-Sprint Exercise Performance

2014 ◽  
Vol 9 (3) ◽  
pp. 387-396 ◽  
Author(s):  
Mark Hayes ◽  
Paul C. Castle ◽  
Emma Z. Ross ◽  
Neil S. Maxwell
Keyword(s):  
Heat Stress ◽  
Exercise Performance ◽  
Peak Power ◽  
Team Sport ◽  
Peak Power Output ◽  
Evaporative Heat Loss ◽  
Physiological Strain ◽  
Type Method ◽  
Sprint Exercise ◽  
Full Protocol

Purpose:To examine the effect of a hot humid (HH) compared with a hot dry (HD) environment, matched for heat stress, on intermittent-sprint performance. In comparison with HD, HH environments compromise evaporative heat loss and decrease exercise tolerance. It was hypothesized that HH would produce greater physiological strain and reduce intermittent-sprint exercise performance compared with HD.Method:Eleven male team-sport players completed the cycling intermittent-sprint protocol (CISP) in 3 conditions, temperate (TEMP; 21.2°C ± 1.3°C, 48.6% ± 8.4% relative humidity [rh]), HH (33.7°C ± 0.5°C, 78.2% ± 2.3% rh), and HD (40.2°C ± 0.2°C, 33.1% ± 4.9% rh), with both heat conditions matched for heat stress.Results:All participants completed the CISP in TEMP, but 3 failed to completed the full protocol of 20 sprints in HH and HD. Peak power output declined in all conditions (P < .05) but was not different between any condition (sprints 1–14 [N = 11]: HH 1073 ± 150 W, HD 1104 ± 127 W, TEMP, 1074 ± 134; sprints 15–20 [N = 8]: HH 954 ± 114 W, HD 997 ± 115 W, TEMP 993 ± 94; P > .05). Physiological strain was not significantly different in HH compared with HD, but HH was higher than TEMP (P < .05).Conclusion:Intermittent-sprint exercise performance of 40 min duration is impaired, but it is not different in HH and HD environments matched for heat stress despite evidence of a trend toward greater physiological strain in an HH environment.

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